HU puts out 6v, amp has a max input of 2.5V Is this gonna be a problem?? 20-30hz??

[roarzorz 10+ year member]

Realize that the HU is not going to put out the "advertised" voltage under any real circumstances. Most likely it is a peak voltage rather than RMS. It also requires the bass to be turned all the way up as well as the volume. The outputs are well into clipping and the level of distortion will be unbearable well before the voltage gets anywhere near 6v.
Unless you have the output gain maxed on that AudioControl unit, it isn't doing anything like 13V either. It's capable but not real-world usable.

and what he said ^ since op seems to need some kinda reassurance. HUs and processors need to be maxed out to reach advertised voltage and even then some of them won't.